The Upanishads, Part 2 (SBE15), by Max Müller, , at sacred-texts.com
1. 'The earth, the sky, heaven, the four quarters, and the intermediate quarters,'--'Agni (fire), Vâyu (air), Âditya (sun), Kandramas (moon), and the stars,'--'Water, herbs, trees, ether, the universal Self (virâg),'--so much with reference to material objects (bhûta).
Now with reference to the self (the body): 'Prâna (up-breathing), Apâna (down-breathing), Vyâna (back-breathing), Udâna (out-breathing), and Samâna (on-breathing),'--'The eye, the ear, mind, speech, and touch,'--'The skin, flesh, muscle, bone, and marrow.' Having dwelt on this (fivefold arrangement of the worlds, the gods, beings, breathings, senses, and elements of the body), a Rishi said: 'Whatever exists is fivefold (pâṅkta) 1.'
(1) By means of the one fivefold set (that referring to the body) he completes the other fivefold set.
50:1 Cf. Brih. Âr. Up. I, 4, 17.